Honesty and an open mind are critical to science. You have to let the data tell you what to think and not the other way around. If you start out expecting x, and you only accept data that confirms x, you’re not a scientist, you’re a politician.
When it comes to the theory of evolution, alas, the last thing most people do is think about it with an open mind. They usually start with that patchwork collection of English translations of Latin translations of ancient Middle Eastern Hebrew writings known as the Bible. Which is odd, because the Bible is very clearly not a science textbook. Read any part of it and you’ll quickly discover the people who wrote it thought the Earth was flat and circled by the sun. Some theologians will try to tell you that no, the Bible authors weren’t really saying the sun went round the Earth or the Earth was flat, they were being metaphorical or some such, but that’s just balderdash so far as I can see. Last time I read any part of it, the book unmistakably said the Earth has corners and ends (“the ends of the earth” etc.) and Joshua stopped the sun in its tracks, and that is unmistakably wrong.
Now I’m not saying that proves the Bible does or does not offer useful religious/moral insights or what have you; that’s a whole different debate. But it does prove what any idiot could have figured out anyway, which is that the Bible is not a science textbook. You won’t find the Laws of Thermodynamics in there, and if Jesus spent any time talking about covalent bonding and molecular orbital theory his disciples forgot to mention it.
So let’s leave aside the Bible for a minute because it’s not a science textbook, it’s a religious text, and frankly it has nothing to do with the history of life. Let’s just rid ourselves of any and all preconceived notions and ask ourselves: where did the species we see today come from? what do we know? and let’s keep this as simple as we can, because I think a lot of the time people lose sight of the forest for the trees, so to speak.
Well, for starters we see that life used to be a lot simpler than it is today. If you go back a couple billion years all you have is single-celled organisms. As you fast forward, new organisms enter the fossil record while other ones die out and disappear. And almost always we find the new organisms that appear in the fossil record are similar to other ones living about the same time but a little bit different. Which is odd, and sort of suggestive.
And if we look around us at what we see today, we find that populations change over time. Insects become resistant to pesticides. Viruses develop the ability to infect new species. Bacteria develop new genes that give them the ability to resist drugs, break down industrial chemicals, or take advantage of conditions in a lab experiment. Sometimes we even see a population of animals develop a new structure their ancestors didn’t have right before our very eyes, or we see a new species emerge that can’t interbreed with the old. New genes, new species, new traits: somehow life is changing across generations.
What’s the most logical way to make sense of all this? Maybe there’s a higher power (Jesus, your mom, the Buddha, a scary race of space aliens, pick whichever you prefer) that has been periodically creating and destroying species. Maybe this higher power sits down every few million years or so and says, “hmmm…I’m kind of bored…let’s create a few new species and make them look a lot like the ones I already created, but a little bit different. And maybe I’ll destroy a few other species while I’m at it.” But why exactly would this higher power do that?
It would make a lot more sense to think about this process of slow change we see going on around us. We see life changing. We’ve seen new genes, new traits and new species emerge. (I linked to a few examples, and there’s plenty of others.) So if this is happening now, it must have been happening in the past. And if life was changing slowly over time in the past the same way it is now, then the patterns we see in the fossil record would make a lot of sense. A lot more sense than the Higher Power that creates and destroys new species every few million years for reasons unknown.
This is kind of the big-picture version of the theory of evolution. There’s a lot of other evidence we could talk about (why does human chromosome 2 look so remarkably like two chimp chromosomes stitched together, for example, or why are there fossils of marsupials and warm-weather plants in Antarctica), but I want to keep this simple so I’ll leave it there. And if you think about it with an open mind, it’s difficult to avoid realizing it makes sense. I do chemistry for a living, not biology, so this is not my bailiwick, but it’s painfully obvious to me that evolution is a good explanation for what we see around us. As I said before (and will say again, because Creationists will almost never acknowledge this) — we’ve seen evolution happen. We’ve seen new genes emerge in lab experiments and in the wild. We’ve seen new species crop up (not often, but then it usually takes a while, and we’ve only been studying nature that closely for a few centuries now). These are not brand-new genes or species from scratch. Rather, they’re modified versions of existing genes and species. Because that’s how evolution works; it modifies what’s already there in a slow and messy way.
Creationists of course are not thinking about this with an open mind. They’re not asking does this theory make sense, they’re asking, how can I find an excuse to reject it? That’s become more and more difficult for them over the last fifty years or so, because we have more and more recorded instances of experiments or field observations where we can see evolution in action. So they usually fall back on one of several popular misconceptions.
1) Evolution can’t create new information.
That’s kind of odd, because we’ve seen it do exactly that. Again, there are now multiple well-known experiments where we’ve seen new genes evolve. The Lenski experiment (link above) is one of them; in this one, e. coli bacteria evolved a new gene that enabled them to use citrate even when oxygen was present. The Barry Hall experiment is another; in this experiment, Hall deleted the gene e. coli needed to digest lactose, and lo and behold, the bacteria evolved the ability to digest lactose all over again. Nylon-eating bacteria are another cool example where a population of bacteria evolved not one but several new genes found nowhere else in Nature that gave them the ability to break down byproducts of nylon manufacture (see link above). The number of antibiotic resistance genes we run across has been steadily increasing, and in many cases we can clearly trace where they came from (modification of an existing gene to make a new one). There are also a growing number of examples where we can easily trace how a particular gene evolved, like the antifreeze protein in Antarctic icefish.
Sometimes Creationists will try to sidestep the issue here by quibbling over what “information” is (since it has a definition in information theory that’s different from the everyday definition). That’s just a stupid semantic waste of time. Evolution of new genes is new “information” no matter which definition you use.
2) Microevolution can happen but macroevolution can’t.
Again, we’ve seen new genes, new traits and new species evolve. If that’s not macroevolution, what do you mean by “macroevolution”? How exactly do you explain the pattern of change over time in the fossil record? Why do you believe that macroevolution “can’t happen”, and what is the magical barrier that prevents it from happening?
3) Evolution says life came from nothing, and that doesn’t make any sense.
You’re right, that doesn’t make any sense. The theory of evolution is not about where life came from. We still don’t know how the first living organisms came into existence or where they came from, although there’s plenty of people working to figure out how that happened. The theory of evolution is not about how the first living organisms came into existence; it’s about what happened afterwards, and about how one species became many over time.
4) Believing in evolution takes just as much faith as believing in creation.
Well, no. It doesn’t take much faith to believe that a process that you’ve seen happening can happen.
5) Some features of living organisms are so complicated they could not have developed through a step-by-step process.
Not true that we know of. The examples Creationists usually like are the blood clotting cascade, the bacterial flagellum and the immune system. But in each and every one of these cases, evolutionary biologists have proposed a series of steps whereby that system could have evolved — and there are other possible pathways you can think of. We can’t see how these systems actually DID evolve because the fossil record doesn’t preserve biochemical stuff unfortunately. But again, we know that new species, genes and traits evolve, we know from the fossil record that this process has been happening as long as life has been around, we see bizarre genetic similarities between closely related organisms, and that’s why evolution is a better way to explain the origin of these biochemical pathways than the alternative proposed by I.D. advocates — the mysterious Higher Power that intervenes periodically to create and destroy new species just for fun. (And seems to do a pretty crappy job. The human genome is littered with “broken genes” that have been rendered inactive by mutations and serve no useful purpose.)
6) Deleterious mutations accumulate in populations over time, therefore all populations of organisms on Earth are gradually deteriorating. Evolution is regressive, not progressive and all species are headed for eventual extinction.
This argument comes from a book by John Sanford at one time of Cornell University; I believe the title is “Genetic Entropy” or some such. It’s popular in Creationist circles but kind of a joke everywhere else, because it’s sort of embarrassing how someone like Sanford, the inventor of the gene gun, could write something so obviously wrong.
Sanford argued that minor deleterious mutations are more common than any other kind, and that natural selection cannot effectively remove them from the gene pool since their effect on fitness, taken individually, is too small. Therefore they will accumulate over time, become very common or”fixed” in the population through random events and the genetic quality of a population will gradually deteriorate, dooming all populations to eventual extinction. Which, to Sanford, clearly implies that The Lord created life as we know it 6,000 years ago. (Never mind that the fossil record shows life has been around for a much longer period of time.) Sanford then opines that perhaps this gradual deterioration explains why Biblical figures like Father Abraham lived to the ripe old age of 800 or whatever.
The problem with this argument is obvious and it’s all around you. Look at cockroaches. Or bacteria. Or rabbits. Or viruses. These are organisms that reproduce much faster than humans. In the case of bacteria, they’ve been through millions of generations over the course of recent recorded history. If populations were really all deteriorating thanks to accumulated deleterious mutations like Sanford claims, bacteria would all be extinct by now. But they’re not. For the most part they’re doing better than ever. So clearly Sanford is wrong, and you don’t even need to know any population genetics to figure that out.
Why would a geneticist make such an obviously flawed argument? Well, Sanford is a born again Christian with an axe to grind. When it comes to evolution, he isn’t doing science, he’s doing politics. He already knows what kind of answer he wants to get, and he’s going to torture the data until it talks.
If you want to overthrow the theory of evolution, you need to come up with an alternate hypothesis that explains the pattern of change in the fossil record, the observed distribution of species and the change we see happening around us right now, and that hypothesis has to make sense. It has to be consistent with what we see. Otherwise you are just doing politics and wasting everybody’s time. And the whole problem for Creationists is that they have to stick to the literal word of the Bible, they’ve nailed their flag to the mast, so to speak, and they’re stuck trying to defend that hopeless flood story in Genesis. (Watching Creationists try to explain how Noah got all the animals on his boat and where all the water came from is entertaining in a sad kind of way.) So they’re stuck doing politics. That’s why they resort to slander and claim they are being persecuted, that evolution is a lie or a conspiracy cooked up by The International Mafia of Science, like some surreal version of Goodfellas with hit men who double as bloodthirsty grad students.
But it doesn’t have to be like that. Whether you believe in a Higher Power or not, we can at least agree on one thing: if there is a Higher Power, it’s probably very smart, and presumably it knows all about evolution because it created that process. Presumably it would want you to think for yourself, and it’s not going to stick you in burning sulfur just because you were audacious enough to accept what you see and keep an open mind.
So keep an open mind. And think about it.